Implantable stimulation devices are devices that generate and deliver electrical stimuli to body nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and deep brain stimulators to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder sublaxation, etc. The present invention may find applicability in all such applications, although the description that follows will generally focus on the use of the invention within a Spinal Cord Stimulation (SCS) system, such as that disclosed in U.S. Pat. No. 6,516,227, which is incorporated herein by reference in its entirety.
Spinal cord stimulation is a well-accepted clinical method for reducing pain in certain populations of patients. As shown in FIGS. 1A and 1B, a SCS system typically includes an Implantable Pulse Generator (IPG) 100, which includes a biocompatible case 30 formed of titanium for example. The case 30 typically holds the circuitry and power source or battery necessary for the IPG to function, although IPGs can also be powered via external RF energy and without a battery. The IPG 100 is coupled to electrodes 106 via one or more electrode leads (two such leads 102 and 104 are shown), such that the electrodes 106 form an electrode array 110. The electrodes 106 are carried on a flexible body 108, which also houses the individual signal wires 112 and 114 coupled to each electrode. In the illustrated embodiment, there are eight electrodes on lead 102, labeled E1-E8, and eight electrodes on lead 104, labeled E9-E16, although the number of leads and electrodes is application specific and therefore can vary.
Portions of an IPG system are shown in FIG. 2 in cross section, and include the IPG 100, an external controller 12, and an external charger 50. The IPG 100 typically includes an electronic substrate assembly 14 including a printed circuit board (PCB) 16, along with various electronic components 20, such as microprocessors, integrated circuits, and capacitors mounted to the PCB 16. Two coils are generally present in the IPG 100: a telemetry coil 13 used to transmit/receive data to/from the external controller 12; and a charging coil 18 for charging or recharging the IPG's power source or battery 26 using the external charger 50. The telemetry coil 13 can be mounted within the header connector 36 as shown.
As just noted, an external controller 12, such as a hand-held programmer or a clinician's programmer, is used to wirelessly send data to and receive data from the IPG 100. For example, the external controller 12 can send programming data to the IPG 100 to set the therapy the IPG 100 will provide to the patient. Also, the external controller 12 can act as a receiver of data from the IPG 100, such as various data reporting on the IPG's status.
The communication of data to and from the external controller 12 occurs via magnetic inductive coupling. When data is to be sent from the external controller 12 to the IPG 100, coil 17 is energized with an alternating current (AC). Such energizing of the coil 17 to transfer data can occur using a Frequency Shift Keying (FSK) protocol for example, such as disclosed in U.S. patent application Ser. No. 11/780,369, filed Jul. 19, 2007, which is incorporated herein by reference in its entirety. Energizing the coil 17 induces an electromagnetic field, which in turn induces a current in the IPG's telemetry coil 13, which current can then be demodulated to recover the original data.
The external charger 50, also typically a hand-held device, is used to wirelessly convey power to the IPG 100 again by magnetic inductive coupling, which power can be used to recharge the IPG's battery 26. The transfer of power from the external charger 50 is enabled by a coil 17′. When power is to be transmitted from the external charger 50 to the IPG 100, coil 17′ is likewise energized with an alternating current. The induced current in the charging coil 18 in the IPG 100 can then be rectified to a DC value, and provided to the battery 26 to recharge the battery.
As is well known, inductive transmission of data or power occurs transcutaneously, i.e., through the patient's tissue 25, making it particular useful in a medical implantable device system.
The inventors consider it unfortunate that the typical implantable medical device system 5 requires two external devices: the external controller 12 and the external charger 50. Both are needed by a typical patient at one time or another with good frequency. The external charger 50 is typically needed to recharge the battery 26 in the IPG 100 on a regular basis, as often as every day depending on the stimulation settings. The external controller 12 can also be needed on a daily basis by the patient to adjust the stimulation therapy as needed at a particular time. Therefore, the patient is encumbered by the need to manipulate two completely independent devices. This means the patient must: learn how to use both devices; carry the bulk of both devices (e.g., when traveling); replace the batteries in both devices and/or recharge them as necessary; pay for both devices, etc. In all, the requirement of two independent external devices is considered inconvenient. This disclosure provides embodiments of a solution to mitigate these problems.